1. Field of the Invention
The present invention relates generally to a crystalline titanate catalyst support having a layered structure. In particular, this invention relates to a catalyst support which has high ion-exchange properties, high surface areas and high hydrogenation activity relative to hydrous titanium oxide supports.
2. Description of the Related Art
Hydrous titanium oxides (HTO) are known to be excellent supports for Co, Mo, Ni, Pd, or vanadia for hydrogenation and oxidation reactions. See Stephens H. P. et al., Ind. & Engr. Chem. Prod. Res. & Dev., Vol. 24, pages 15-19 (1985). Specifically, Dosch et al. have used ion exchange techniques to prepare Co-HTO, Mo/Ni-HTO, and Pd-HTO for use as Fischer-Tropsch catalysts and coal liquefaction catalysts. See "Hydrous Metal Oxide-Supported Catalysts: Part I. A Review of Preparation Chemistry and Physical and Chemical Properties", SAND89-2399, Sandia National Laboratories (1990) and "Hydrous Metal Oxide-Supported Catalysts: Part II. A Review of Catalytic Properties and Applications", SAND89-2400, Sandia National Laboratories (1990). See also U.S. Pat. No. 4,511,455. Gruber, K. A., "The Selective Catalytic Reduction of Nitric Oxide With Ammonia in the Presence of Oxygen", M. S. Thesis, Chem. Eng. Dept. Texas A&M University, (August, 1989) used HTO as a support for vanadia in the selective catalytic reduction of nitric oxide with ammonia in the presence of oxygen.
HTO based catalysts are known to provide high activities and surface areas. However, one of the drawbacks of using HTO materials as catalyst supports in high-temperature applications is the change in activity which occurs as the material proceeds through the amorphous to crystalline transition usually to anatase titania. This phase conversion generally results in a decrease in surface area, and very dense material. The phase conversion accelerates as temperature increases, which minimizes the number of practical applications for crystalline HTO. For example, coal liquefaction reactions require a temperature between 300.degree. and 500.degree. C.
U.S. Pat. No. 4,696,810 (Shirasaki et al.) discloses metal titanates prepared by high temperature reactions between oxides such as BaO and TiO. The metal titanates in Shirasaki et al. do not have a layered structure, are typically refractory, have surface areas below 10 m.sup.2 /g, and poor ion exchange properties (less than 1 milliequivalent per gram). The possibility of preparing crystalline titanate compounds that do not undergo a phase transition would thus be desirable.